This invention relates to a disc-type chipper for cutting uniform chips from a log, and in particular, to an improved blade mounting assembly for supporting reversible knife blades upon the front face of the disc.
In U.S. Pat. No. 4,047,670 to Svensson there is disclosed a disc type chipper that employs reversible type knives. The blade of each knife has a Z-shaped configuration having angularly disposed cutting surfaces that makes the blade extremely difficult to grip and support in assembly. The knives are clamped between a lower chip guide and an upper clamping bar which have precisely machined jaws capable of accepting the complex shape of the blade therebetween. In assembly the jaws are arranged to clamp upon the center leg of one or more blades. Because of the complex blade geometry, the blades can easily become misaligned between the jaws during the clamping operation. Typically, Svensson utilizes at least two blades in each cutting station. The blades are provided in short segments and are mounted end to end between the clamping jaws in assembly. Accordingly, the blade alignment and clamping problems become compounded when the jaws are being closed.
Due to the odd configuration of the Svensson knife blades, both the blades themselves and the clamping jaws are difficult and costly to manufacture. The center leg which supports the two offset and angularly disposed cutting edges represents a weak sector and is subject to failure under load or extended use. Accordingly, both initial cost of a chipper using these reversible knives and the cost of operating and maintaining the machines are relatively high.